1. Field
Example embodiments relate to a poly-crystalline silicon (Si) thin film, a thin film transistor (TFT) formed from a poly-crystalline silicon (Si) thin film and methods of manufacturing the same. Other example embodiments relate to a method of manufacturing a poly-crystalline Si thin film, having a substantially large area, that may be crystallized at a substantially low temperature and a method of manufacturing a TFT using the same.
2. Description of the Related Art
Recently, research has been conducted on a low temperature poly-silicon thin film transistor (LTPS TFT) that may be used in an organic light emitting display device, a liquid crystal display device or the like. Research continues to be conducted in regard to a system-on-glass (SOG) having no external driver integrated circuit (IC). By integrating the external driver IC into a display panel, it may not be necessary to use a connector between the display panel and the external driver IC. As such, physical pixel error may be reduced, increasing reliability of the display device. An SOG, in which a display system including a controller, and data and gate driver ICs is integrated into the display panel, may be desirable. In order to integrate the display system, a mobility of the LTPS greater than 400 cm2/Vsec and/or increased uniformity of the LTPS, is desirable.
LTPS having a desired qualities (and/or characteristics) may be difficult to manufacture using excimer laser annealing (ELA), sequential lateral solidification (SLS), metal-induced lateral crystallization (MILC) or the like.
A method of manufacturing poly-crystalline Si may be characterized as a method in which poly-crystalline Si is directly deposited, or a method in which amorphous Si is deposited to be crystallized. In the latter method, by forming an amorphous Si on a substrate and performing excimer laser annealing (ELA) (e.g., a heat-treatment with respect to the amorphous Si by using an excimer laser), the amorphous Si may be crystallized and converted into poly-crystalline Si.
The excimer laser used in the ELA emits a square beam that is about 1 cm wide. Heat-treatment with the square beam, which is performed with respect to the amorphous Si thin film having a substantially large area, may be performed sequentially on each divided portion included in a region having check patterns, which each correspond to the size of the square beam.
According to the heat-treatment performed with respect to each sequential divided portion, crystallization may not occur on a boundary between units of a region on which a unit of heat-treatment is performed. There may be a boundary having a crystallization state different from those of the other boundaries, even though crystallization may occur on the boundary. Due to the boundary between units of the region, parts of the poly-crystalline Si may have poor qualities (and/or characteristics). Thus, in an active matrix liquid crystal display device (AMLCD), or in an active matrix organic light emission diode display device (AMOLED), transistors for respective pixels may not uniformly operate. As such, an image may not be uniformly displayed.